Inside mold form



March 1943- I Q M. BROSIUS I 2,315,394

INSIDE MOLD FORM Filed April 25, 1940 2 Sheets-Sheet 1 0 /\5 IX va 000000000 0 7 O .7 Inventor Mul'l'd V rew/21.9

A iiomey Patented Mar. 30, 1943 UNITED, STATES PATENT OFFICE INSIDE MOLD FORM Murray Brosius, Nashville, Tenn. Application April 25, 1940, Serial No. 331,648 4 Claims. (01. 18-42) My invention-relates to improvements in the acter, having transverse reinforcements of the same material as the form and molded in the same operation, especially for the making of a one-piece plastic or other moldable composition aeroplane wing characterized by trussed spars and trussed ribs and diagonal braces formed internally therein and further, characterized by greater strength for a given weight.

Other important objects-and advantages of my invention will be apparent from a reading of the following description taken in connection with the drawings, wherein for purposes of illustration I have shown preferred embodiments of apparatus in accordance with the present invention.

In the drawings: I

half of amold for molding an aeroplane wing, and showing the inside mold form or core in place. a Y

Figure 2 is an enlarged transverse vertical sectional view taken through Figure 1 approximately on theline 2-2 and looking toward the right in the direction of the arrow and showing the upper half of the mold in place.

Figure 3 is an enlarged fragmentary transverse vertical sectional view taken through Figure 1 apthe line 'l'l and looking upwardly in the direction of the arrow.

Figure 8 is a fragmentary top plan view of a, still further type of inside mold form.

Figure 9 is a fragmentary enlarged transverse vertical sectionalview taken through Figure 8 approximately on the line 99.

Figure 10 is a fragmentary enlarged transverse vertical sectional view taken through Figure 1 approximately on the line 10-! 0.

In accordance with the present invention the upper and lower sections 6 and 1, respectively, of the mold 5 may be of any suitable materials and have their meeting faces cut away at 8 and 9, respectively, to the desired outside contour of the upper and lower surfaces of such a molded object as an aeroplane wing or wing section. The inside mold form or core Ill may be made of wax, composition, plastic, or of rigid material, or of metal parts held together and positioned relative to each other by means of assembling and spacing members which are capable of being dissolved by means of a solvent, or made fluid by application of heat, and capable of dislodgment bypouring, withdrawal by suction, vaporization, or expulsion by centrifugal force. The inside mold form or core l0 may be molded or cast of thermoplastics, waxes, parafilne, glues,-comp'osite materials, crystalline substances, soluble substances Figure 1 is a top plan view showing the lower proximately on theline 33 and looking toward the right in the direction of the arrow.

Figure 4 is a fragmentary top plan view showing a different arrangement of inside mold form or core.

Figure 5 is an enlarged transverse vertical sectional view taken through Figure 4 approximately on the line 5-5. I

Figure 6 is a top plan view showing another type of inside mold form or core in place in the lower half of amold.

Figure 7 is a longitudinal vertical sectional or of lead or bismuth and alloys which can be removed by heat without harming the molded object or removed by means of solvents such as ketones, hydroxy esters, tetrachlorethane, and ethylene dichloride-alcohol type solvents capable of dissolving a core of cellulose acetate or the like without injuring the molded object, or by a combination of application of heat and solvents and centrifugal force. The material chosen for the inside mold form or core depends on the plastic or composition from which the object to be molded is to be made, whether it is a thermosetting or a thermoplastic plastic, cold molded, molded by evaporation, or molded with heat and/or pressure; or made of fiber or composite material impregnated with plastics or a protein composition to be made into a plastic polyamide by impregnatin-g the same with phenol or dibasic acid,

inforcing net work, flanges, transverse bars and view taken through Figure 6 approximately on '55 reinforcing members on the inside of the hollow nated by the numerals II, I! and It, in Figures 2; '3 and 10, formed of the material from which the molded object is to be molded or ofother material, are placed in the core before pouring to give the desired thickness to the skin of the wing and the slugs may be left in place as an integral part of the outer surface of the molded object and removed when desired to provide inspection holes. The element ll comprises a pin extending slightly above and below the core in and capped at both ends with slugs engaging the upper and lower mold. sections so as to space these sections the desired amount from the mold core and thereby predetermine the thickness of the upper and lower skins of the resultant molded form. When either of the slugs is removed the pin can be withdrawn through the resulting hole. In the event the pin and slug assembly is left in place it acts to keep the top and,bottom skins of the wing section ,or the like properly braced and spaced. The

rectangular plug l2, shown in Figure 3 of the to the wing by a bolt or the like (not shown) passing through such circular opening.

Metal reinforcing or. other reinforcing may be placed in cavitiesin the inside mold form or core III or through holes resulting from removal of the plugs II, I! and llbefore the molding operation is carried out, so that the reinforcement will be integrally formed in the braces are designated i8, i9, 2|, 22, 22", 23,,and 28.

Holes tlirough the core for forming a trussed rib comprise those designated l5 and IS. The inclining and inclining connected channels 32, and 33 shown in Figure 5 ,of the drawings define intermal truss braces which result from the molding operation, and the opening of these channels 32 and 38 into the rib forming channels H and i5 result in the formation of internal trussed ribs, thereby reducing bulk and.

weight while providing adequate or additional strength. For forming untrussed flying spars or continuations oi the trussed spars, grooves 20 extending out through the end of the form are provided. If desired all three types of spars may be made in one spar, each being a continuation of the other, as indicated by the presence of the corresponding grooves in the various figures of the drawings, brace accommodating holes being provided to open into the brace forming grooves 22b in Figures 6 and 7, and in other groove formations to provide for joining ribs, spars, and (the transverse rib reinforcements. The rib forming grooves 22, in the form of the invention shown in Figures 1 .and 2 of the drawings may be provided with grooves on both sides of the inside mold form and connected by the rib brace forming .holes 23 similar to the spar brace forming hole I! already alluded to in connection with Figure 5 01' the drawings. I

For producing flying and transverse sectional rib braces, registeringgroo'ves are provided on aeroplane 'wing or the like when the casting operation has been completed. In this way a and larger mold so as to apply a skin. thereto of different material. Referring to' Figures 1 and 2 of the drawings, illustrating a sectional for mof inside moldin: form or core, it will be evident that thechannels M, II, and it which extend from the top and bottom and side surfaces of the upper and lower mold sections, 'extend substantially both sides of the inside mold form with some of these grooves communicating with each other as indicated by the numeral 24 in Figure l and other being unconnected as indicated at the point designated by. the numeral 25 in Figure 1,

and with orwithout the brace \iorming holes 23.

All-over transverse braces areprovided by intersecting sides or grooves 26 as indicated in.

' are-provided by depressions or grooves 29 in the upper and/or lower surfaces of the inside mold form or core as indicated in Figure 8 of the drawings and also in Figure 9 therein, wherein the mold. form is enerally designated by the numeral I00. I! desired, lugs 30, shown in Figure l ofthe drawings, may be molded by the full length of the form to be molded and are defined by longitudinally divided parts of the inside mold form, the channels it and i5 providing for the molding of solid spars. In a modification oi. this arrangement shown in Figures 4 and 5, the channels i4 and I5 are replaced by grooves l1 and I8, respectively, formed on the top and bottom of the mold form with having suitable depressions in the upper and lower mold sections 8 and I so that they will be molded in the finished, product to provide for attachment of ailerons.

A relatively large rectangular hole 3| or slot formed all the way through the inside mold form is provided for molding wing slots, and a tight fitting slug I2 is inserted through the outside wall through the opening l2 as indicated in Figure 3, with suillcient spacing being provided -in the corresponding hole in the mole form as indicated in Figure 3 to provide wing slots in the. same manner as for attaching exterior bracing. Pieces .or slugs mounted on the surfaces of the core form to get .the thickness of the outside skin or surface of the finished w product may be of material from which the wing vertical holes i9 opening through these grooves,

thereby'providing trussed spars of the lattice, woven or webbed type in the molded object.

is/molded or of other material and may be left in place as an integral part of the wing or removed for inspection hole mountings. Plugs or pieces may be mounted in the longitudinally 'Holes through the core in for molding truss 7;, outward ends of the longitudinal grooves as in the opposite endsof' the transverse grooves to provide upon their removal holes through which the material from the inside mold can flow. by gravity or by reason of application or centrifugal force to the solutionor other fluid form of the mold material. 7

Suitable material for molding aeroplane wings in accordance with the present invention comprise fiber saturated with Bakelite, protein and polymers of the Nylon" type, phenolformaldehyde synthetic resins and also pro teins saturated with formaldehyde in whichis embedded fiber.

Although I'have shown and described herein preferred embodiments of my invention, it is to be definitely understood that I do not -desire to limit the application of the invention thereto, except as may be required by the scope of the subjoined claims.

Having described the invention, what I claim an upper section having its under surface formed to define the contour and plan shape of the upper wall of the wing, means supportably mounting said upper section on said lower section, a core within the. space defined by the contour forming area of the under surface of said upper section and the contour forming area of the upper surface of said lower section, said secting core being of material capable of dissolution and removal without disturbing the mated relation of the upper and lower walls of the aeroplane wing: maintaining the vertical spacing of the upper and lower faces of the core from the contour forming areas of the upper and lower mold sections, said spacing means comprising vertical slugs extending through accommodating open ings formed in said core, said .slugs supportably resting on the upper surface of said lower mold section and being supportably engaged with the upper mold section.

2. A mold as described by claim 1 wherein said slugs comprise vertical pins traversing accommodating openings formed in said core and have enlarged removable heads acting as spacing blocks between the upper and lower faces of the mold core and the corresponding surfaces of the mold sections.

3; A mold as described by claim 1 wherein said mold core has its upper and lower faces formed with longitudinal and transverse interchannels to define interlocking internal spars and ribs.

4. A mold as described by claim 1 wherein said core has its upper and lower faces formed withtransverse and longitudinal intersectin channels to define internal interlocking ribs and spars, said mold core further being formed 'with intersecting diagonal channels planes, the last mentioned channels leading into some of saidtransverse and longitudinal channels to define internal cross bracing integral with the spars and ribs.

MURRAY BROSIUS.

spacing means for determining and" in horizontal 

